Integrated circuit chip having two types of memory cells

ABSTRACT

An integrated circuit chip includes a first type memory cell and a second type memory cell. The first type memory cell includes a first reference line landing pad and a first word line landing pad. The first reference line landing pad of the first type memory cell and the first word line landing pad of the first type memory cell are aligned along a first direction. The second type memory cell includes a first reference line segment extending along the first direction and a first word line landing pad. The first word line landing pad of the second type memory cell and the first reference line segment of the second type memory cell are spaced apart along a second direction different from the first direction.

RELATED APPLICATIONS

The instant application is related to U.S. Patent Application titled “METHODS AND APPARATUS FOR FINFET SRAM ARRAYS IN INTEGRATED CIRCUITS,” filed on Dec. 6, 2011, U.S. application Ser. No. 13/312,810, now U.S. Pat. No. 8,693,235. The entire contents of the above-referenced application are incorporated by reference herein.

BACKGROUND

The semiconductor integrated circuit (IC) industry has produced a wide variety of digital devices to address issues in a number of different areas. Some of these digital devices are electrically coupled to static random access memory (SRAM) devices for the storage of digital data. In some applications in an IC chip, a plurality of SRAM devices are implemented based on different design criteria. For example, at least one SRAM device of the plurality of SRAM devices is designed to have faster data access than all other SRAM device(s) of the plurality of SRAM devices; and at least one SRAM device of the plurality of SRAM devices is designed to occupy less area per stored bit than all other SRAM device(s) of the plurality of SRAM devices.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 is a block diagram of an integrated circuit (IC) chip having two static random access memory (SRAM) devices, in accordance with some embodiments.

FIG. 2 is a schematic circuit diagram of a memory cell, in accordance with some embodiments.

FIG. 3 is a top view of a first type memory cell, with all the depictions regarding components at and over a first metal layer of a chip omitted, in accordance with some embodiments.

FIG. 4 is a top view of a second type memory cell, with all the depictions regarding components at and over the first metal layer of the chip omitted, in accordance with some embodiments.

FIG. 5 is a top view of the first type memory cell in FIG. 3, with emphasis of the components at the first metal layer and a second metal layer of the chip, in accordance with some embodiments.

FIG. 6 is a top view of the second type memory cell in FIG. 4, with emphasis of the components at the first metal layer and the second metal layer of the chip, in accordance with some embodiments.

FIG. 7 is a top view of the first type memory cell in FIG. 3, with emphasis of the components at a third metal layer and a fourth metal layer of the chip, in accordance with some embodiments.

FIG. 8 is a cross-sectional view of a portion of a chip, in accordance with some embodiments.

FIG. 9 is a top view of a portion of a first memory device, with emphasis of the components at a first metal layer of a chip, in accordance with some embodiments.

FIG. 10 is a layout diagram of a portion of a layout design for forming the conductive features of the first metal layer in FIG. 9, in accordance with some embodiments.

FIGS. 11A-11E are top views of a portion of the first memory device in FIG. 9 at various stages of forming the first metal layer of the chip according to a first manufacturing process, in accordance with some embodiments.

FIGS. 12A-12E are top views of a portion of the first memory device in FIG. 9 at various stages of forming the first metal layer of the chip according to a second manufacturing process, in accordance with some embodiments.

FIG. 13 is a top view of a portion of a second memory device, with emphasis of the components at the first metal layer of the chip, in accordance with some embodiments.

FIG. 14 is a layout diagram of a portion of a layout design for forming the conductive features of the first metal layer in FIG. 13, in accordance with some embodiments.

FIG. 15 is a flowchart of a method of forming an IC chip according to the first manufacturing process in FIGS. 11A-11E, in accordance with some embodiments.

FIG. 16 is a flowchart of a method of forming an IC chip according to the second manufacturing process in FIGS. 12A-12E, in accordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

In accordance with some embodiments, an integrated circuit chip includes a first type memory cell and a second type memory cell. The first type memory cell includes a first reference line landing pad and a first word line landing pad. The first reference line landing pad of the first type memory cell and the first word line landing pad of the first type memory cell are aligned along a first direction. The second type memory cell includes a first reference line segment extending along the first direction and a first word line landing pad. The first word line landing pad of the second type memory cell and the first reference line segment of the second type memory cell are spaced apart along a second direction different from the first direction.

FIG. 1 is a block diagram of an IC chip 100 having two memory devices 110 and 140, in accordance with some embodiments. Other devices and components of IC chip 100 are not depicted in FIG. 1. Memory devices 110 and 140 are SRAM devices formed of SRAM memory cells. For clarity, some details of memory devices 110 and 140 are not depicted in FIG. 1.

Memory device 110 includes a memory cell array 112, a plurality of write assist circuits 114, and a plurality of conductive lines 116 electrically coupling memory cell array 112 with the plurality of write assist circuits 114. Memory cell array 112 includes a plurality of first type memory cells arranged into rows along a direction X and columns along a direction Y. Each column of the columns of first type memory cells of memory cell array 112 has at least one conductive line of the plurality of conductive lines 116 extending along direction Y and electrically coupling the column and a corresponding write assist circuit of write assist circuits 114.

In some embodiments, the plurality of conductive lines 116 are bit lines of memory device 110, and each write assist circuit of the plurality of write assist circuits 114 is configured to set a voltage level of the corresponding bit line of memory device 110 to be less than a ground reference level. In some embodiments, the plurality of conductive lines 116 are bit lines of memory device 110, and each write assist circuit of the plurality of write assist circuits 114 are supply voltage lines of memory device 110, and each write assist circuit of the plurality of write assist circuits 114 is configured to set a voltage level of the corresponding supply voltage line of memory device 110 to be less than a supply voltage level.

Memory device 140 includes a memory cell array 142. Memory cell array 142 includes a plurality of second type memory cells arranged into rows along direction X and columns along direction Y. Memory device 140 is free from having a counterpart circuit of the write assist circuit 114 of memory device 110.

In some embodiments, a first type memory cell used to implement memory device 110 occupies an area less than that of a second type memory cell used to implement memory device 140. In some embodiments, a pass gate device of the second type memory cell used to implement memory device 140 has a driving capability greater than that of a pass gate device of the first type memory cell used to implement memory device 110. In some embodiments in a single chip, the first type memory cell is referred to as a smaller memory cell, and the second type memory cell is referred to as a faster memory cell.

Further details regarding the first type memory cell are described in conjunction with FIGS. 2, 3, 5, and 7. Further details regarding the second type memory cell are described in conjunction with FIGS. 2, 4, and 6.

FIG. 2 is a schematic circuit diagram of a memory cell 200, in accordance with some embodiments. In some embodiments, memory cell 200 corresponds to the first type memory cell or the second type memory cell in FIG. 1.

Memory cell 200 includes a storage circuit 210 having data nodes ND and NDB, two pass gate devices PG1 and PG2, a supply voltage node NVDD, a reference voltage node NVSS, a first bit line BL, a second bit line BLB, and a word line WL. Storage circuit 210 is electrically coupled between supply voltage node NVDD and reference voltage node NVSS. Pass gate device PG1 is electrically coupled with data node ND, bit line BL, and word line WL. Pass gate device PG2 is electrically coupled with data node NDB, bit line BLB, and word line WL.

Storage circuit 210 includes two P-type metal oxide semiconductor (PMOS) transistors P1 and P2 and two N-type metal oxide semiconductor (NMOS) transistors N1 and N2. Transistors P1, P2, N1, and N2 form a cross latch having two cross-coupled inverters. Transistors P1 and N1 form a first inverter while transistors P2 and N2 form a second inverter. Drains of transistors P1 and N1 are coupled together and form data node ND. Drains of transistors P2 and N2 are coupled together and form data node NDB. Gates of transistors P1 and N1 are coupled together and to drains of transistors P2 and N2. Gates of transistors P2 and N2 are coupled together and to drains of transistors P1 and N1. Sources of transistor P1 and P2 are coupled with supply voltage node. In some embodiments, supply voltage node NVDD is configured to receive a supply voltage VDD. Sources of transistors N1 and N2 are coupled with reference voltage node. In some embodiments, reference voltage node NVSS is configured to receive a ground reference voltage VSS.

Pass gate devices PG1 and PG2 are N-type transistors. A drain of pass gate device PG1 is electrically coupled with bit line BL at node NBL. A source of pass gate device PG1 is electrically coupled with data node ND. A drain of pass gate device PG2 is electrically coupled with bit line BLB at node NBLB. A source of pass gate device PG2 is electrically coupled with data node NDB. A gate of pass gate device PG1 and a gate of pass gate device PG2 are electrically coupled with a word line WL. Gates of pass gate devices PG1 and PG2 are control terminals thereof configured to receive a control signal for turning on or off pass gate devices PG1 and PG2.

In some embodiments, in a memory array, such as memory cell array 112 or memory cell array 142, having a plurality of memory cells each having a circuit schematic illustration the same as memory cell 200, bit lines BL and BLB are coupled to each drain of pass gate devices PG1 and PG2 of memory cells in a column of the memory array, and word line WL is coupled to each gate of pass gate devices PG1 and PG2 of memory cells in a row of the memory array.

Memory cell 200 is a single port SRAM cell illustrated as an example. In some embodiments, the present application is applicable to a multiple-port SRAM cell having one or more write ports and/or one or more read ports.

FIG. 3 is a top view of a first type memory cell 300, with all the depictions regarding components at and over a first metal layer of a chip omitted, in accordance with some embodiments. Moreover, the depictions regarding via plugs connecting various components depicted in FIG. 3 and the first metal layer are omitted. The first metal layer of the chip will be further illustrated in conjunction with FIG. 8. In some embodiments, first type memory cell 300 is an implementation of a first type memory cell in FIG. 1 having a circuit schematic illustration as memory cell 200 depicted in FIG. 2. Some components of first type memory cell 300 are not shown in FIG. 3 for clarity of FIG. 3.

Memory cell 300 includes a substrate (not labeled) having P-well regions 302 and 304 and an N-well region 306. Memory cell 300 includes a plurality of active structures 312, 314, 316, and 318 extending along a direction Y; a plurality of gate structures 322, 324, 326, and 328 extending along a direction X; a plurality of active contact structures 332, 334, 336, 338, 342, 344, 346, and 348; and a plurality of gate contact structures 352, 354, 356, and 358.

Active structures 312 and 314 are in P-well regions 302 and 304 for forming NMOS transistors. Active structures 316 and 318 are in N-well region 306 forming PMOS transistors. Active structures 312, 314, 316, and 318 are semiconductor fins formed on the substrate. The number of fins for each transistor depicted in FIG. 3 is provided as an example. In some embodiments, any number of fins is within the scope of various embodiments. In some embodiments, active structures 312, 314, 316, and 318 are integrally formed with the substrate.

Gate structure 326 overlaps active structure 316 and functions as a gate of transistor P1. Active contact structures 346 and 342 overlap active structure 316 and correspond to a source and a drain of transistor P1. Gate structure 328 overlaps active structure 318 and functions as a gate of transistor P2. Active contact structures 348 and 344 overlap active structure 318 and correspond to a source and a drain of transistor P2. Gate contact structure 356 connects gate structure 328 and active contact structures 342. Gate contact structure 358 connects gate structure 326 and active contact structures 344. Gate structure 326 also overlaps active structure 312 and functions as a gate of transistor N1. Active contact structures 334 and 342 overlap active structure 312 and correspond to a source and a drain of transistor N1. Gate structure 328 overlaps active structure 314 and functions as a gate of transistor N2. Active contact structures 338 and 336 overlap active structure 314 and correspond to a source and a drain of transistor N2.

Accordingly, active contact structures 346 and 348 correspond to node NVDD; and active contact structures 334 and 338 correspond to node NVSS.

Gate structure 322 overlaps active structure 312 and functions as a gate of pass gate device PG1. Active contact structures 332 and 342 overlap active structure 312 and correspond to a source and a drain of pass gate device PG1. Gate contact structure 352 contacts gate structure 322 and functions as a landing pad for gate structure 322. Gate structure 324 overlaps active structure 314 and functions as a gate of pass gate device PG2. Active contact structures 336 and 344 overlap active structure 314 and correspond to a source and a drain of pass gate device PG2. Gate contact structure 354 contacts gate structure 324 and functions as a landing pad for gate structure 324.

Accordingly, active contact structure 332 corresponds to node NBL; and active contact structure 336 corresponds to node NBLB.

Memory cell 300 has a cell width X1 measurable along direction X and a cell height Y1 measurable along direction Y. In some applications, a memory macro is formed by repeating and abutting memory cells having a configuration identical or mirrored-identical to memory cell 300, and thus cell width X1 is also referred to as a cell pitch along direction X, and cell height Y1 is also referred to as a cell pitch along direction Y. In some embodiments, a ratio of cell width X1 to cell height Y1 is greater than one.

FIG. 4 is a top view of a second type memory cell 400, with all the depictions regarding components at and over the first metal layer of the chip omitted, in accordance with some embodiments. Moreover, the depictions regarding via plugs connecting various components depicted in FIG. 4 and the first metal layer are omitted. In some embodiments, second type memory cell 400 is an implementation of a second type memory cell in FIG. 1 having a circuit schematic illustration as memory cell 200 depicted in FIG. 2. Some components of first type memory cell 400 are not shown in FIG. 4 for clarity of FIG. 4.

Memory cell 400 includes a substrate (not labeled) having P-well regions 402 and 404 and an N-well region 406. Memory cell 400 includes a plurality of active structures 412 a, 412 b, 414 a, 414 b, 416, and 418 extending along direction Y; a plurality of gate structures 422, 424, 426, and 428 extending along a direction X; a plurality of active contact structures 432, 434, 436, 438, 442, 444, 446, and 448; and a plurality of gate contact structures 452, 454, 456, and 458. Except active structures 412 a, 412 b, 414 a, and 414 b, each component depicted in FIG. 4 and a counterpart component depicted in FIG. 3 that have the same last two-digit reference number correspond to each other, and detailed description thereof is thus omitted.

Compared with first type memory cell 300, second type memory cell 400 replaces active structure 312 with active structures 412 a and 412 b and replaces active structure 314 with active structures 414 a and 414 b.

Gate structure 422 overlaps active structures 412 a and 412 b and functions as a gate of pass gate device PG1. Active contact structures 432 and 442 overlap active structures 412 a and 412 b and correspond to a source and a drain of pass gate device PG1. Gate structure 422, active structures 412 a and 412 b, and active contact structures 432 and 442 are configured as two transistors connected in parallel. In some embodiments, pass gate device PG1 of second type memory cell 400 is configured to have a driving capability greater than that of pass gate device PG1 of first type memory cell 300. In some embodiments, the driving capability of pass gate device PG1 of second type memory cell 400 is about twice the driving capability of pass gate device PG1 of first type memory cell 300.

Gate contact structure 452 contacts gate structure 422 and functions as a landing pad for gate structure 422. Gate structure 424 overlaps active structures 414 a and 414 b and functions as a gate of pass gate device PG2. Active contact structures 436 and 444 overlap active structures 414 a and 414 b and correspond to a source and a drain of pass gate device PG2. Gate contact structure 454 contacts gate structure 424 and functions as a landing pad for gate structure 424. In some embodiments, pass gate device PG2 of second type memory cell 400 is configured to have a driving capability greater than that of pass gate device PG2 of first type memory cell 300 in a manner similar to pass gate device PG1. In some embodiments, the driving capability of pass gate device PG2 of second type memory cell 400 is about twice the driving capability of pass gate device PG2 of first type memory cell 300.

Gate structure 426 also overlaps active structures 412 a and 412 b and functions as a gate of transistor N1. Active contact structures 434 and 442 overlap active structures 412 a and 412 b and correspond to a source and a drain of transistor N1. Gate structure 428 overlaps active structures 414 a and 414 b and functions as a gate of transistor N2. Active contact structures 438 and 436 overlap active structures 414 a and 414 b and correspond to a source and a drain of transistor N2. In some embodiments, transistor N1 of second type memory cell 400 is configured to have a driving capability greater than that of transistor N1 of first type memory cell 300. In some embodiments, transistor N2 of second type memory cell 400 is configured to have a driving capability greater than that of transistor N2 of first type memory cell 300.

Memory cell 400 has a cell width X2 measurable along direction X and a cell height Y2 measurable along direction Y. In some applications, a memory macro is formed by repeating and abutting memory cells having a configuration identical or mirrored-identical to memory cell 400, and thus cell width X2 is also referred to as a cell pitch along direction X, and cell height Y2 is also referred to as a cell pitch along direction Y. In some embodiments, a ratio of cell width X2 to cell height Y2 is greater than one.

In some embodiments, cell height Y1 equals cell height Y2. In some embodiments, a ratio of cell width X2 to cell width X1 is greater than 1.15. In some embodiments, the ratio of cell width X2 to cell width X1 ranges from 1.23 to 1.25. In some embodiments, in a given manufacturing process, the ratio of cell width X2 to cell width X1 is determinable based on the additional width usable to accommodate the formation of additional active structures, such as active structures 412 a/412 b versus active structure 312 for transistor N1 and pass gate device PG1 or active structures 414 a/414 b versus active structure 314 for transistor N2 and pass gate device PG2.

FIG. 5 is a top view of the first type memory cell 300 in FIG. 3, with emphasis of the components at the first metal layer and a second metal layer of the chip, in accordance with some embodiments. Components in FIG. 5 that are the same or similar to those in FIG. 3 are given the same reference numbers, and detailed description thereof is thus omitted. Some components of memory cell 300 are not depicted in FIG. 5, or depicted in dotted lines, or not labeled for clarity of FIG. 5.

Memory cell 300 includes a plurality of conductive line segments 502, 504, 506, 512, 514, 516, 518, 522, 524, and 526. Conductive line segments 502, 504, and 506 extend along direction Y in a first metal layer of a chip in which first type memory cell 300 and second type memory cell 400 are formed. Conductive line segments 512, 514, 516, and 518 function as landing pads and are also in the first metal layer. Conductive lines 512, 514, 516, and 518 are also referred to as landing pads in this disclosure. Conductive line segments 522, 524, and 526 extend along direction X in a second metal layer of the chip. The second metal layer is over the first metal layer. In some embodiments, each segment of conductive line segments 522, 524, and 526 is a portion of a corresponding reference line or word line that extends along direction X and electrically coupled with all memory cells of the same row. Memory cell 300 includes a plurality of via plugs V0 connecting conductive line segments of the first metal layer with corresponding active contact structures 332, 334, 336, and 338 and gate contact structures 352 and 354. Memory cell 300 further includes a plurality of via plugs V1 connecting various landing pads 512, 514, 516, and 518 of the first metal layer with various conductive line segments 522, 524, and 526 of the second metal layer.

The second metal layer of the chip, via plugs V0, and via plugs V1 will be further illustrated in conjunction with FIG. 8.

Conductive line segment 502 extends along direction Y and is electrically coupled with active contact structure 332 through a corresponding via plug V0. Conductive line segment 502 is thus electrically coupled with node NBL of first type memory cell 300. In some embodiments, conductive line segment 502 is a bit line segment that constitutes a portion of a bit line BL of a column of first type memory cells where first type memory cell 300 is disposed. Conductive line segment 504 extends along direction Y and is electrically coupled with active contact structure 336 through a corresponding via plug V0. Conductive line segment 504 is thus electrically coupled with node NBLB of first type memory cell 300. In some embodiments, conductive line segment 504 is a bit line segment that constitutes a portion of a bit line BLB of the column of first type memory cells where first type memory cell 300 is disposed.

Conductive line segment 506 extends along direction Y and is electrically coupled with active contact structures 346 and 348 through corresponding via plugs V0. Conductive line segment 506 is thus electrically coupled with node NVDD of first type memory cell 300. In some embodiments, conductive line segment 506 is a supply voltage line segment that constitutes a portion of a supply voltage line of the column of first type memory cells where first type memory cell 300 is disposed.

Landing pad 512 and landing pad 514 are aligned along direction Y. Landing pad 512 is electrically coupled with gate contact structure 352 through a corresponding via plug V0. Landing pad 512 is thus electrically coupled with the gate or control terminal of pass gate device PG1 of first type memory cell 300. In some embodiments, landing pad 512 is also referred to as a word line landing pad of first type memory cell 300. Landing pad 514 is electrically coupled with active contact structure 334 through a corresponding via plug V0. Landing pad 514 is thus electrically coupled with node NVSS of first type memory cell 300. In some embodiments, landing pad 514 is also referred to as a reference line landing pad of first type memory cell 300.

Landing pad 516 and landing pad 518 are aligned along direction Y. Landing pad 516 is electrically coupled with gate contact structure 354 through a corresponding via plug V0. Landing pad 516 is thus electrically coupled with the gate or control terminal of pass gate device PG2 of first type memory cell 300. In some embodiments, landing pad 516 is also referred to as another word line landing pad of first type memory cell 300. Landing pad 518 is electrically coupled with active contact structure 338 through a corresponding via plug V0. Landing pad 518 is thus electrically coupled with node NVSS of first type memory cell 300. In some embodiments, landing pad 514 is also referred to as another reference line landing pad of first type memory cell 300.

Conductive line segment 522 extends along direction X and is electrically coupled with reference line landing pad 514 through a corresponding via plug V1. Conductive line segment 522 is thus electrically coupled with node NVSS of first type memory cell 300. In some embodiments, conductive line segment 522 is a reference line segment that constitutes a portion of a reference voltage line of a row of first type memory cells where first type memory cell 300 is disposed. Conductive line segment 524 extends along direction X and is electrically coupled with reference line landing pad 518 through a corresponding via plug V1. Conductive line segment 524 is thus also electrically coupled with node NVSS of first type memory cell 300. In some embodiments, conductive line segment 524 is another reference line segment that constitutes a portion of another reference voltage line of the row of first type memory cells where first type memory cell 300 is disposed.

Conductive line segment 526 extends along direction X and is electrically coupled with word line landing pads 512 and 516 through corresponding via plugs V1. Conductive line segment 526 is thus electrically coupled with control terminals of pass gate devices PG1 and PG2 of first type memory cell 300. In some embodiments, conductive line segment 526 is a word line segment that constitutes a portion of a word line of the row of first type memory cells where first type memory cell 300 is disposed. Conductive line segment 526 has a line width W1 measurable along direction Y.

FIG. 6 is a top view of the second type memory cell 400 in FIG. 4, with emphasis of the components at the first metal layer and the second metal layer of the chip, in accordance with some embodiments. Components in FIG. 6 that are the same or similar to those in FIG. 4 are given the same reference numbers, and detailed description thereof is thus omitted. Some components of memory cell 400 are not depicted in FIG. 6, or depicted in dotted lines, or not labeled for clarity of FIG. 6.

Memory cell 400 includes a plurality of conductive line segments 602, 604, 606, 607, 608, 612, 616, 622, and 626. Conductive line segments 602, 604, 606, 607, and 608 extend along direction Y in the first metal layer of the chip in which first type memory cell 300 and second type memory cell 400 are formed. Conductive line segments 612 and 616 function as landing pads and are also in the first metal layer. Conductive lines 612 and 616 are also referred to as landing pads in this disclosure. Conductive line segments 622 and 626 extend along direction X in the second metal layer of the chip. In some embodiments, each segment of conductive line segments 622 and 626 is a portion of a corresponding reference line or word line that extends along direction X and electrically coupled with all memory cells of the same row. Memory cell 400 includes a plurality of via plugs V0 connecting conductive line segments of the first metal layer with corresponding active contact structures 432, 434, 436, and 438 and gate contact structures 452 and 454. Memory cell 400 further includes a plurality of via plugs V1 connecting various landing pads 612 and 616 and conductive lines 607 and 608 of the first metal layer with various conductive line segments 622 and 626 of the second metal layer.

Conductive line segment 602 extends along direction Y and is electrically coupled with active contact structure 432 through a corresponding via plug V0. Conductive line segment 602 is thus electrically coupled with node NBL of second type memory cell 400. In some embodiments, conductive line segment 602 is a bit line segment that constitutes a portion of a bit line BL of a column of second type memory cells where second type memory cell 400 is disposed. Conductive line segment 604 extends along direction Y and is electrically coupled with active contact structure 436 through a corresponding via plug V0. Conductive line segment 604 is thus electrically coupled with node NBLB of second type memory cell 400. In some embodiments, conductive line segment 604 is a bit line segment that constitutes a portion of a bit line BLB of the column of second type memory cells where second type memory cell 400 is disposed.

Conductive line segment 606 extends along direction Y and is electrically coupled with active contact structures 446 and 448 through corresponding via plugs V0. Conductive line segment 606 is thus electrically coupled with node NVDD of second type memory cell 400. In some embodiments, conductive line segment 606 is a supply voltage line segment that constitutes a portion of a supply voltage line of the column of second type memory cells where second type memory cell 400 is disposed.

Conductive line segment 607 extends along direction Y and is electrically coupled with active contact structure 434 through a corresponding via plug V0. Conductive line segment 607 is thus electrically coupled with node NVSS of second type memory cell 400. In some embodiments, conductive line segment 607 is a reference line segment that constitutes a portion of a reference line of a column of second type memory cells where second type memory cell 400 is disposed. Conductive line segment 608 extends along direction Y and is electrically coupled with active contact structure 438 through a corresponding via plug V0. Conductive line segment 608 is thus also electrically coupled with node NVSS of second type memory cell 400. In some embodiments, conductive line segment 608 is another reference line segment that constitutes a portion of another reference line of the column of second type memory cells where second type memory cell 400 is disposed.

Landing pad 612 is electrically coupled with gate contact structure 452 through a corresponding via plug V0. Landing pad 612 is thus electrically coupled with the gate or control terminal of pass gate device PG1 of second type memory cell 400. Landing pad 616 is electrically coupled with gate contact structure 454 through a corresponding via plug V0. Landing pad 616 is thus electrically coupled with the gate or control terminal of pass gate device PG2 of second type memory cell 400. In some embodiments, landing pad 612 and landing pad 616 are also referred to as word line landing pads of second type memory cell 400.

Compared with word line landing pad 512 and reference line landing pad 514 of first type memory cell 400, word line landing pad 612 and reference line segment 607 are spaced apart along direction X. Also, compared with word line landing pad 516 and reference line landing pad 518 of first type memory cell 400, word line landing pad 616 and reference line segment 608 are spaced apart along direction X.

Conductive line segment 622 extends along direction X and is electrically coupled with reference line segments 607 and 608 through corresponding via plugs V1. Conductive line segment 622 is thus electrically coupled with node NVSS of second type memory cell 400. In some embodiments, conductive line segment 622 is a reference line segment that constitutes a portion of a reference voltage line of a row of second type memory cells where second type memory cell 400 is disposed.

Conductive line segment 626 extends along direction X and is electrically coupled with word line landing pads 612 and 616 through corresponding via plugs V1. Conductive line segment 626 is thus electrically coupled with control terminals of pass gate devices PG1 and PG2 of second type memory cell 400. In some embodiments, conductive line segment 626 is a word line segment that constitutes a portion of a word line of the row of second type memory cells where second type memory cell 400 is disposed. Conductive line segment 626 has a line width W2 measurable along direction Y.

In some embodiments, the cell height Y1 of first type memory cell 300 is the same as the cell height Y2 of second type memory cell 400. In some embodiments, for the same cell height, first type memory cell 300 is configured to correspond to two reference line segments 522 and 524 and one word line segment 526 while second type memory cell 400 is configured to correspond to only one reference line segment 622 and one word line segment 626. As such, in some embodiments, line width W2 of word line segment 626 of the second type memory cell 400 is set to be greater than line width W1 of word line segment 526 of first type memory cell 300. In some embodiments, a ratio of line width W2 to line width W1 is greater than 1.5.

Furthermore, reference line segment 622 has a line width W3 measurable along direction Y. In some embodiments, line width W2 is set to be greater than line width W3. Reference line segment 607 has a line width W4 measurable along direction X; and bit line segment 602 has a line width W5 measurable along direction X. In some embodiments, line width W5 is set to be greater than line width W4. In some embodiments, a ratio of line width W5 to line width W4 is greater than 1.1.

FIG. 7 is a top view of the first type memory cell 300 in FIG. 3, with emphasis of the components at a third metal layer and a fourth metal layer of the chip, in accordance with some embodiments. Components in FIG. 7 that are the same or similar to those in FIG. 5 are given the same reference numbers, and detailed description thereof is thus omitted. Some components of memory cell 300 are not depicted in FIG. 7, or depicted in dotted lines, or not labeled for clarity of FIG. 7.

Memory cell 300 includes a plurality of conductive line segments 712, 716, 722, and 726. Conductive line segment 712 extends along direction Y in the third metal layer of the chip in which first type memory cell 300 and second type memory cell 400 are formed. Conductive line segment 716 functions as a landing pad and is also in the third metal layer. Conductive line segment 716 is also referred to as a landing pad in this disclosure. Conductive line segments 722 and 726 extend along direction X in the fourth metal layer of the chip. In some embodiments, each segment of conductive line segments 722 and 726 is a portion of a corresponding reference line or word line that extends along direction X and electrically coupled with all memory cells of the same row. Memory cell 300 includes a plurality of via plugs V2 connecting conductive line segments of the second metal layer with corresponding conductive line segments of the third metal layer. Memory cell 300 further includes a plurality of via plugs V3 connecting conductive line segments of the third metal layer with corresponding conductive line segments of the fourth metal layer.

The third metal layer of the chip, the fourth metal layer, via plugs V2, and via plugs V3 will be further illustrated in conjunction with FIG. 8.

Conductive line segment 712 extends along direction Y and is electrically coupled with conductive lines 522 and 524 through corresponding via plugs V2. Conductive line segment 712 is thus electrically coupled with node NVSS of second type memory cell 300. In some embodiments, conductive line segment 712 is a reference line segment that constitutes a portion of a reference line of a column of first type memory cells where first type memory cell 300 is disposed.

Landing pad 716 is electrically coupled with conductive line segment 526 through a corresponding via plug V2. Landing pad 716 is thus electrically coupled with the gates or control terminals of pass gate devices PG1 and PG2 of first type memory cell 300. In some embodiments, landing pad 716 is referred to as another word line landing pad of second type memory cell 300.

Conductive line segment 722 extends along direction X and is electrically coupled with reference line segment 712 through a corresponding via plug V3. Conductive line segment 722 is thus electrically coupled with node NVSS of first type memory cell 300. In some embodiments, conductive line segment 722 is a reference line segment that constitutes a portion of a reference voltage line of a row of first type memory cells where first type memory cell 300 is disposed.

Conductive line segment 726 extends along direction X and is electrically coupled with word line landing pad 716 through a corresponding via plug V3. Conductive line segment 726 is thus electrically coupled with control terminals of pass gate devices PG1 and PG2 of first type memory cell 300. In some embodiments, conductive line segment 726 is a word line segment that constitutes a portion of a word line of the row of first type memory cells where first type memory cell 300 is disposed.

Conductive line segment 726 has a line width W6 measurable along direction Y. Conductive line segment 722 has a line width W7 measurable along direction Y. In some embodiments, line width W6 is set to be greater than line width W7.

First type memory cell 300 and second type memory cell 400 illustrated in conjunction with FIGS. 3-7 are provided as an example. In some embodiments, some of various conductive lines and/or landing pads are omitted as long as the resulting first type memory cell 300 and second type memory cell 400 are still consistent with the circuit schematic depicted in FIG. 1.

FIG. 8 is a cross-sectional view of a portion of a chip 800, in which the first type memory cell and the second type memory cell as illustrated in the present application are formed, in accordance with some embodiments. Some components of chip 800 are not depicted for clarity of FIG. 8.

Chip 800 includes a substrate 802, various isolation features 804 buried in substrate 802, a plurality of gate structures 812 formed over substrate 802, a plurality of active contact structures 814 over substrate 802, and a plurality of gate contact structures 816 over various gate structures 812. Chip 800 also includes a plurality of conductive layers, which is also referred to as metal layers in this disclosure, and a plurality of via layers over substrate 802.

The conductive layers of chip 800 include a first metal layer having conductive features M1, a second metal layer having conductive features M2, a third metal layer having conductive features M3, and a fourth metal layer having conductive features M4. The via layers of chip 800 include a base via layer having via plugs V0, a first via layer having via plugs V1, a second via layer having via plugs V2, and a third via layer having via plug V3. Via plugs V0 are arranged to connect at least some of active conductive structures 814 and/or gate conductive structures 816 with corresponding first metal layer conductive features M1. Via plugs V1 are arranged to connect at least some first metal layer conductive features M1 with corresponding second metal layer conductive features M2. Via plugs V2 are arranged to connect at least some second metal layer conductive features M2 with corresponding third metal layer conductive features M3. Via plug V3 is arranged to connect a third metal layer conductive feature M3 with a corresponding fourth metal layer conductive feature M4.

FIG. 8 is used as to demonstrate the spatial relationship among various metal layers and via layers. In some embodiments, the numbers of conductive features at various layers are not limited to the example depicted in FIG. 8. In some embodiments, there are one or more metal layers and one or more via layers over the fourth metal layer conductive structure M4.

FIG. 9 is a top view of a portion of a first memory device 900, with emphasis of the components at a first metal layer of a chip, in accordance with some embodiments. In some embodiments, first memory device 900 corresponds to first memory device 110 depicted in FIG. 1.

Memory device 900 includes memory cells 910 a, 910 b, 910 c, and 910 d. Memory device 900 also includes a plurality of landing pads 922 a, 922 b, 922 c, 922 d, 924 a, 924 b, 924 c, 924 d, 926 ab, 926 cd, and 928; a plurality of line segments 932 a, 932 b, 932 c, 932 d, 934 a, 934 b, 934 c, 934 d, 936 a, 936 b, 936 c, and 936 d.

Moreover, memory device 900 includes bit lines 942, 944, 952, and 954 and supply voltage lines 946 and 956. Bit line 942 is formed of at least conductive line segments 932 a and 932 c; bit line 944 is formed of at least conductive line segments 934 a and 934 c; bit line 952 is formed of at least conductive line segments 932 b and 932 d; and bit line 954 is formed of at least conductive line segments 934 b and 934 d. Supply voltage line 946 is formed of at least conductive line segments 936 a and 936 c; and supply voltage line 956 is formed of at least conductive line segments 936 b and 936 d.

Each memory cell of memory cells 910 a, 910 b, 910 c, and 910 d is a first type memory cell and has a configuration similar to first type memory cell 300 illustrated in conjunction with FIGS. 3, 5, and 7. For memory cell 910 a, landing pads 922 a, 924 a, 926 ab, and 928 correspond to landing pads 512, 514, 516, and 518 in FIG. 5; and conductive line segments 932 a, 934 a, and 936 a correspond to conductive segments 502, 504, and 506 in FIG. 5. For memory cell 910 b, landing pads 922 b, 924 b, 926 ab, and 928 corresponding to landing pads 512, 514, 516, and 518 in FIG. 5; and conductive line segments 932 b, 934 b, and 936 b correspond to conductive segments 502, 504, and 506 in FIG. 5. For memory cell 910 c, landing pads 922 c, 924 c, 926 cd, and 928 corresponding to landing pads 512, 514, 516, and 518 in FIG. 5; and conductive line segments 932 c, 934 c, and 936 c correspond to conductive segments 502, 504, and 506 in FIG. 5. For memory cell 910 d, landing pads 922 d, 924 d, 926 cd, and 928 corresponding to landing pads 512, 514, 516, and 518 in FIG. 5; and conductive line segments 932 d, 934 d, and 936 d correspond to conductive segments 502, 504, and 506 in FIG. 5.

Therefore, detailed description of various landing pads and conductive segments depicted in FIG. 9 is omitted.

FIG. 10 is a layout diagram of a portion of a layout design 1000 for forming the conductive features of the first metal layer in FIG. 9, in accordance with some embodiments.

Layout design 1000 includes a first set of conductive layout patterns 1012, 1014, 1016, and 1018; a second set of conductive layout patterns 1022, 1024, 1032, 1034, and 1036; a first set of cutting layout patterns 1042 a-1042 h; and a second set of cutting layout patterns 1044 a-1044 f. Conductive layout patterns 1012, 1014, 1016, and 1018 extend along direction Y and are usable to form conductive lines 942, 944, 954, and 952 in FIG. 9. Conductive layout patterns 1022, 1024, 1032, 1034, and 1036 extend along direction Y and are usable to form conductive lines 946 and 956 in FIG. 9 and conductive lines on which landing pads 924 a-928 are based. First set of conductive layout patterns 1012, 1014, 1016, and 1018 and second set of conductive layout patterns 1022, 1024, 1032, 1034, and 1036 are used during two distinctive patterning processes. First set of cutting layout patterns 1042 a-1042 h and second set of cutting layout patterns each extend along direction X and are arranged along direction Y in an alternating manner. First set of cutting layout patterns 1042 a-1042 h and second set of cutting layout patterns are used in conjunction with conductive layout patterns 1032, 1034, and 1036 in order to form various landing pads by trimming the resulting conductive lines based on conductive layout patterns 1032, 1034, and 1036 or by forming blocking structures to intervene the formation of conductive lines based on conductive layout patterns 1032, 1034, and 1036.

FIGS. 11A-11E are top views of a portion of the first memory device 900 in FIG. 9 at various stages of forming the first metal layer of the chip according to a first manufacturing process, in accordance with some embodiments. The formation of landing pads 926 ab, 926 cd, and 928 based on conductive layout pattern 1034 and cutting layout patterns 1042 d, 1042 e, 1044 c, and 1044 d are illustrated in conjunction with FIGS. 11A-11E as an example.

In FIG. 11A, a conductive line 1102 is formed over a substrate based on conductive layout pattern 1034. In FIG. 11B, a first lithographic process is performed to form in a photoresist layer 1104 a set of openings based on cutting layout patterns 1044 c and 1044 d. The openings in photoresist layer 1104 are transferred to a mask layer 1112 (FIG. 11D) to form a first set of etching windows in the mask layer 1112. In FIG. 11C, a second lithographic process is performed to form in a photoresist layer 1106 a set of openings based on cutting layout patterns 1042 d and 1042 e. The openings in photoresist layer 1106 are transferred to the mask layer 1112 to form a second set of etching windows in the mask layer 1112. In FIG. 11D, the resulting mask layer 1112 now includes four etching windows defined based on cutting layout patterns 1042 d, 1042 e, 1044 c, and 1044 d.

In FIG. 11E, portions of the conductive line 1102 that are exposed by the set of etching windows in the mask layer 1112 are removed to trim conductive line 1102 into landing pads 1112 a, 1112 b, 1112 c, 1112 d, and 1112 e. In this embodiment, landing pads 1112 b, 1112 c, and 1112 d correspond to landing pads 926 cd, 928, and 926 ab in FIG. 9.

FIGS. 12A-12E are top views of a portion of the first memory device 900 in FIG. 9 at various stages of forming the first metal layer of the chip according to a second manufacturing process, in accordance with some embodiments. The formation of landing pads 926 ab, 926 cd, and 928 based on conductive layout pattern 1034 and cutting layout patterns 1042 d, 1042 e, 1044 c, and 1044 d are illustrated in conjunction with FIGS. 12A-12E as an example.

In FIG. 12A, a first lithographic process is performed to form a first set of blocking structures 1212 over a dielectric layer 1202 based on a first set of cutting layout patterns 1044 c and 1044 d. In FIG. 12B, a second lithographic process is performed to form a second set of blocking structures 1214 over dielectric layer 1202 based on a second set of cutting layout patterns 1042 d and 1042 e. In FIG. 12C, a mask layer 1222 is formed over the blocking structures 1212 and 1214. The mask layer 1222 has an opening 1224 therein, and the opening 1224 is formed based on conductive line layout pattern 1034.

In FIG. 12D, recesses 1232 a-1232 e are formed in portions of the dielectric layer 1202 that are exposed by the opening 1224 of mask layer 1222 and not covered by the blocking structures 1212 and 1214. In FIG. 12E, the recesses are filled with a conductive material to form landing pads 1234 a, 1234 b, 1234 c, 1234 d, and 1234 e. In some embodiments, the conductive material includes Cu, Ni, TaN, TiN, W, or a combination thereof. In this embodiment, landing pads 1234 b, 1234 c, and 1234 d correspond to landing pads 926 cd, 928, and 926 ab in FIG. 9.

FIG. 13 is a top view of a portion of a second memory device 1300, with emphasis of the components at the first metal layer of the chip, in accordance with some embodiments. In some embodiments, second memory device 1300 corresponds to second memory device 140 depicted in FIG. 1.

Memory device 1300 includes memory cells 1310 a, 1310 b, 1310 c, and 1310 d. Memory device 1300 also includes a plurality of landing pads 1322 a, 1322 b, 1322 c, 1322 d, 1324 ab, and 1324 cd; a plurality of line segments 1332 a-1332 d, 1334 a-1334 d, 1336 a-1336 d, 1342 a-1342 d, and 1344 a-1344 d.

Moreover, memory device 1300 includes bit lines 1352, 1354, 1362, and 1364; supply voltage lines 1356 and 1366; and reference lines 1357, 1358, 1367, and 1368. Bit line 1352 is formed of at least conductive line segments 1342 a and 1342 c; bit line 1354 is formed of at least conductive line segments 1344 a and 1344 c; bit line 1362 is formed of at least conductive line segments 1342 b and 1342 d; and bit line 1364 is formed of at least conductive line segments 1344 b and 1344 d. Supply voltage line 1356 is formed of at least conductive line segments 1336 a and 1336 c; and supply voltage line 1366 is formed of at least conductive line segments 1336 b and 1336 d. Reference line 1357 is formed of at least conductive line segments 1332 a and 1332 c; reference line 1358 is formed of at least conductive line segments 1334 a and 1334 c; reference line 1367 is formed of at least conductive line segments 1332 b and 1332 d; and reference line 1368 is formed of at least conductive line segments 1344 b and 1344 d.

Each memory cell of memory cells 1310 a, 1310 b, 1310 c, and 1310 d is a second type memory cell and has a configuration similar to second type memory cell 400 illustrated in conjunction with FIGS. 4 and 6. For memory cell 1310 a, landing pads 1322 a and 1324 ab correspond to landing pads 612 and 616 in FIG. 6; conductive line segments 1342 a, 1344 a, and 1336 a correspond to conductive segments 602, 604, and 606 in FIG. 6; and conductive line segments 1332 a and 1334 a correspond to conductive segments 607 and 608 in FIG. 6. For memory cell 1310 b, landing pads 1322 b and 1324 ab correspond to landing pads 612 and 616 in FIG. 6; conductive line segments 1342 b, 1344 b, and 1336 b correspond to conductive segments 602, 604, and 606 in FIG. 6; and conductive line segments 1342 b and 1334 b correspond to conductive segments 607 and 608 in FIG. 6. For memory cell 1310 c, landing pads 1322 c and 1324 cd correspond to landing pads 612 and 616 in FIG. 6; conductive line segments 1342 c, 1344 c, and 1336 c correspond to conductive segments 602, 604, and 606 in FIG. 6; and conductive line segments 1332 c and 1334 c correspond to conductive segments 607 and 608 in FIG. 6. For memory cell 1310 d, landing pads 1322 d and 1324 cd correspond to landing pads 612 and 616 in FIG. 6; conductive line segments 1342 d, 1344 d, and 1336 d correspond to conductive segments 602, 604, and 606 in FIG. 6; and conductive line segments 1342 d and 1334 d correspond to conductive segments 607 and 608 in FIG. 6. Therefore, detailed description of various landing pads and conductive segments depicted in FIG. 13 is omitted.

FIG. 14 is a layout diagram of a portion of a layout design 1400 for forming the conductive features of the first metal layer in FIG. 13, in accordance with some embodiments.

Layout design 1400 includes a first set of conductive layout patterns 1412, 1414, 1416, 1418, 1422, 1424, and 1426; a second set of conductive layout patterns 1432, 1434, 1436, 1442, 1444, and 1446; and a set of cutting layout patterns 1452 a-1452 g. First set of conductive layout patterns 1412, 1414, 1416, 1418, 1422, 1424, and 1426 extend along direction Y and are usable to form conductive lines 1352, 1354, 1362, and 1364 in FIG. 13 and conductive lines on which landing pads 1322 a-1324 cd are based. Second set of conductive layout patterns 1432, 1434, 1436, 1442, 1444, and 1446 extend along direction Y and are usable to form conductive lines 1357, 1358, 1356, 1367, 1368, and 1366 in FIG. 13. First set of conductive layout patterns 1412, 1414, 1416, 1418, 1422, 1424, and 1426 and second set of conductive layout patterns 1432, 1434, 1436, 1442, 1444, and 1446 are used during two distinctive patterning processes. Cutting layout patterns 1452 a-1452 g extend along direction X and are used in conjunction with conductive layout patterns 1422, 1424, and 1426 in order to form various landing pads by trimming the resulting conductive lines based on conductive layout patterns 1422, 1424, and 1426 or by forming blocking structures to intervene the formation of conductive lines based on conductive layout patterns 1422, 1424, and 1426. In some embodiments, various conductive lines and landing pads are formed in a manner similar to those illustrated in conjunction with FIGS. 11A-11E or FIGS. 12A-12E.

FIG. 15 is a flowchart of a method 1500 of forming an IC chip according to the first manufacturing process in FIGS. 11A-11E, in accordance with some embodiments. It is understood that additional operations may be performed before, during, and/or after the method 1500 depicted in FIG. 15, and that some other processes may only be briefly described herein.

Method 1500 begins with operation 1510, where various transistors of memory device 110 and 120 (FIG. 1) are formed. Operation 1510 includes forming pass gate devices PG1/PG2 for first type memory cells of first memory device 110 (operation 1512) and forming pass gate devices PG1/PG2 for second type memory cells of second memory device 120 (operation 1514). In some embodiments, each pass gate device of the pass gate devices of the first type memory cells has a first driving capability; and each pass gate device of the pass gate devices of the second type memory cells has a second driving capability. In some embodiments, the second driving capability is greater than the first driving capability.

Method 1500 proceeds to operation 1520, where conductive lines at a first metal layer of the chip are formed based on conductive line layout patterns. For example, operation 1520 includes operation 1522, where conductive lines for first type memory cells of first memory device 110 are formed based on conductive line layout patterns 1012-1036 (FIG. 10). Operation 1520 includes operation 1524, where conductive lines for second type memory cells of second memory device 120 are formed based on conductive line layout patterns 1412-1446 (FIG. 14). A resulting conductive line 1102 is depicted in FIG. 11A as an example.

Method 1500 proceeds to operation 1530, where a first lithographic process is performed to form a first set of etching windows in a mask layer based on a first set of cutting layout patterns. For example, two etching windows in mask layer 1112 (FIG. 11D) are formed based on cutting layout patterns 1044 c and 1044 d (FIG. 10). Operation 1530 includes forming the mask layer 1112 for first type memory cells of first memory device 110 in operation 1532 and forming the mask layer 1112 for second type memory cells of second memory device 120.

Method 1500 proceeds to operation 1540, where a second lithographic process is performed to form a second set of etching windows in the mask layer based on a second set of cutting layout patterns. For example, two other etching windows in mask layer 1112 (FIG. 11D) are formed based on cutting layout patterns 1042 d and 1042 e (FIG. 10). Operation 1540 includes forming the mask layer 1112 for first type memory cells of first memory device 110 in operation 1542. In some embodiments, operation 1534 is performed as part of operation 1540 and is not part of operation 1530.

Method 1500 proceeds to operation 1550, where portions of the conductive lines that are exposed by the etching windows in the mask layer 1112 are removed. A plurality of landing pads are formed as a result of trimming the conductive lines based on operations 1530-1550. As an example, FIG. 11E is a diagram of a plurality of resulting landing pads 1112 a-1112 e.

FIG. 16 is a flowchart of a method of forming an IC chip according to the second manufacturing process in FIGS. 12A-12E, in accordance with some embodiments. It is understood that additional operations may be performed before, during, and/or after the method 1600 depicted in FIG. 16, and that some other processes may only be briefly described herein.

Method 1600 begins with operation 1610, where various transistors of memory device 110 and 120 (FIG. 1) are formed. Operation 1610 includes forming pass gate devices PG1/PG2 for first type memory cells of first memory device 110 (operation 1612) and forming pass gate devices PG1/PG2 for second type memory cells of second memory device 120 (operation 1614). In some embodiments, each pass gate device of the pass gate devices of the first type memory cells has a first driving capability; and each pass gate device of the pass gate devices of the second type memory cells has a second driving capability. In some embodiments, the second driving capability is greater than the first driving capability.

Method 1600 proceeds to operation 1620, where a first lithographic process is performed to form a first set of blocking structures over a dielectric layer, such as forming blocking structures 1212 over a dielectric layer 1202 in FIG. 12, based on the first set of cutting layout patterns, such as cutting layout patterns 1044 c and 1044 d. Operation 1620 includes forming blocking structures for first type memory cells of first memory device 110 in operation 1622 and forming blocking structures for second type memory cells of second memory device 120 in operation 1624. In some embodiments, operation 1622 is performed based on cutting layout patterns 1044 a-1044 f in FIG. 10. In some embodiments, operation 1624 is performed based on cutting layout patterns 1452 a-1452 g in FIG. 14.

Method 1600 proceeds to operation 1630, where a second lithographic process is performed to form a second set of blocking structures over the dielectric layer, such as forming blocking structures 1214 over dielectric layer 1202 in FIG. 12, based on the second set of cutting layout patterns, such as cutting layout patterns 1042 d and 1042 e. Operation 1630 includes forming additional blocking structures for first type memory cells of first memory device 110 in operation 1632. In some embodiments, operation 1632 is performed based on cutting layout patterns 1042 a-1044 h in FIG. 10. In some embodiments, operation 1624 is performed as part of operation 1630 and is not part of operation 1620.

Method 1600 proceeds to operation 1640, where a mask layer over the blocking structures is formed. For example, a mask layer 1222 is formed over blocking structures 1212 and 1214 as depicted in FIG. 12C. The mask layer 1222 has an opening 1224 therein, and opening 1224 is formed based on a conductive line layout pattern. For example, operation 1640 includes forming openings based on conductive line layout patterns 1032, 1034, and 1036 in FIG. 10 for first type memory cells of first memory device 110 (operation 1642). Also, operation 1640 includes forming openings based on conductive line layout patterns 1422, 1424, and 1426 in FIG. 14 for second type memory cells of second memory device 120 (operation 1644).

Method 1600 proceeds to operation 1650, where recesses are formed in portions of the dielectric layer that are exposed by the openings of the mask layer and not covered by the blocking structures. For example, recesses 1232 a-1232 e are formed in portions of the dielectric layer 1202 as depicted in FIG. 12D.

Method 1600 proceeds to operation 1660, where the recesses are filled with a conductive material to form landing pads. For example, landing pads 1234 a, 1234 b, 1234 c, 1234 d, and 1234 e are formed by filling recesses 1232 a-1232 e as depicted in FIG. 12E. In some embodiments, the conductive material includes Cu, Ni, TaN, TiN, W, or a combination thereof.

The configurations and operations described above are illustrated as individual examples. In some embodiments, a memory cell or a memory device is implemented by adopting the features of one or more of the individual examples illustrated above.

In accordance with one embodiment, an integrated circuit chip includes a first type memory cell and a second type memory cell. The first type memory cell includes a storage circuit having a first data node, a second data node, a supply voltage node, and a reference voltage node; a first pass gate device having a first terminal, a second terminal, and a control terminal; a first reference line landing pad electrically coupled with the reference voltage node of the first type memory cell; and a first word line landing pad electrically coupled with the control terminal of the first pass gate device of the first type memory cell. The first terminal of the first pass gate device of the first type memory cell is electrically coupled with the first data node of the first type memory cell. The first reference line landing pad of the first type memory cell and the first word line landing pad of the first type memory cell are aligned along a first direction. The second type memory cell includes a storage circuit having a first data node, a second data node, a supply voltage node, and a reference voltage node; a first pass gate device having a first terminal, a second terminal, and a control terminal; a first reference line segment extending along the first direction and electrically coupled with the reference voltage node of the second type memory cell; and a first word line landing pad electrically coupled with the control terminal of the first pass gate device of the second type memory cell. The first terminal of the first pass gate device of the second type memory cell is electrically coupled with the first data node of the second type memory cell. The first word line landing pad of the second type memory cell and the first reference line segment of the second type memory cell are spaced apart along a second direction different from the first direction.

In accordance with another embodiment, an integrated circuit chip includes a first memory device and a second memory device. The first memory device includes a row of first type memory cells, a first reference line, a second reference line, and a first word line. Each memory cell of the row of first type memory cells includes a first reference line landing pad; a second reference line landing pad; a first word line landing pad; and a second word line landing pad. The first reference line landing pad of the memory cell of the row of first type memory cells and the first word line landing pad of the memory cell of the row of first type memory cells are aligned along a first direction. The second reference line landing pad of the memory cell of the row of first type memory cells and the second word line landing pad of the memory cell of the row of first type memory cells are aligned along the first direction. The first reference line extends along a second direction different from the first direction and is electrically coupled with the first reference line landing pad of the memory cell of the row of first type memory cells. The second reference line extends along the second direction and is electrically coupled with the second reference line landing pad of the memory cell of the row of first type memory cells. The first word line extends along the second direction and is electrically coupled with the first word line landing pad of the memory cell of the row of first type memory cells and the second word line landing pad of the memory cell of the row of first type memory cells. The second memory device includes a row of second type memory cells, a first reference line, and a first word line. Each memory cell of the row of second type memory cells includes a first reference line segment, a second reference line segment, a first word line landing pad, and a second word line landing pad. The first reference line segment of the memory cell of the row of second type memory cells and the first word line landing pad of the memory cell of the row of second type memory cells are spaced apart along the second direction. The second reference line segment of the memory cell of the row of second type memory cells and the second word line landing pad of the memory cell of the row of second type memory cells are spaced apart along the second direction. The first reference line extends along the second direction and is electrically coupled with the first reference line segment of the memory cell of the row of second type memory cells and the second reference line segment of the memory cell of the row of second type memory cells. The first word line extends along the second direction and is electrically coupled with the first word line landing pad of the memory cell of the row of second type memory cells and the second word line landing pad of the memory cell of the row of second type memory cells.

In accordance with another embodiment, a method of manufacturing an integrated circuit chip is disclosed. The method includes forming a first memory device having a plurality of first type memory cells and forming a second memory device having a plurality of second type memory cells. Forming the first memory device includes forming a plurality of first reference line landing pads and a plurality of first word line landing pad of the plurality of first type memory cells based on a first conductive line layout pattern, a first set of cutting layout patterns, and a second set of cutting layout patterns. The first conductive line layout pattern extends along a first direction. Each one of the first set of cutting layout patterns and each one of the second set of cutting layout patterns extends along a second direction different from the first direction. The first set of cutting layout patterns and the second set of cutting layout patterns are arranged along the first direction in an alternating manner. Forming the second memory device includes forming a plurality of first word line landing pad of the plurality of second type memory cells based on a second conductive line layout pattern and a third set of cutting layout patterns. The second conductive line layout pattern extends along the first direction, and each one of the third set of cutting layout patterns extends along the second direction.

Various types of transistors are discussed in this disclosure as example. In some embodiments, the implementations using other types of transistors different from those illustrated in the present disclosure are within the scope of the subject application.

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure. 

What is claimed is:
 1. An integrated circuit chip, comprising: a first type memory cell, comprising: a storage circuit having a first data node, a second data node, a supply voltage node, and a reference voltage node; a first pass gate device having a first terminal, a second terminal, and a control terminal, the first terminal of the first pass gate device of the first type memory cell being electrically coupled with the first data node of the first type memory cell; a first reference line landing pad electrically coupled with the reference voltage node of the first type memory cell; and a first word line landing pad electrically coupled with the control terminal of the first pass gate device of the first type memory cell, the first reference line landing pad of the first type memory cell and the first word line landing pad of the first type memory cell being aligned along a first direction; and a second type memory cell, comprising: a storage circuit having a first data node, a second data node, a supply voltage node, and a reference voltage node; a first pass gate device having a first terminal, a second terminal, and a control terminal, the first terminal of the first pass gate device of the second type memory cell being electrically coupled with the first data node of the second type memory cell; a first reference line segment extending along the first direction and electrically coupled with the reference voltage node of the second type memory cell; and a first word line landing pad electrically coupled with the control terminal of the first pass gate device of the second type memory cell, the first word line landing pad of the second type memory cell and the first reference line segment of the second type memory cell being spaced apart along a second direction different from the first direction.
 2. The integrated circuit chip of claim 1, wherein the first pass gate device of the second type memory cell has a driving capability greater than that of the first pass gate device of the first type memory cell.
 3. The integrated circuit chip of claim 1, wherein the first type memory cell has a cell height measurable along the first direction and a cell width measurable along the second direction; the second type memory cell has a cell height measurable along the first direction and a cell width measurable along the second direction; and the cell width of the second type memory cell is greater than the cell width of the first type memory cell.
 4. The integrated circuit chip of claim 3, wherein the cell height of the first type memory cell is the same as the cell height of the second type memory cell; the first type memory cell further comprises: a first reference line segment extending along the second direction and electrically coupled with the first reference line landing pad of the first type memory cell; and a first word line segment extending along the second direction and electrically coupled with the first word line landing pad of the first type memory cell and the second word line landing pad of the first type memory cell, the first word line segment of the first type memory cell having a line width measurable along the first direction; the second type memory cell further comprises: a third reference line segment extending along the second direction and electrically coupled with the first reference line segment of the second type memory cell; and a first word line segment extending along the second direction and electrically coupled with the first word line landing pad of the second type memory cell and the second word line landing pad of the second type memory cell, the first word line segment of the second type memory cell having a line width measurable along the first direction; and the line width of the first word line segment of the second type memory cell is greater than the line width of the first word line segment of the first type memory cell.
 5. The integrated circuit chip of claim 1, wherein the first type memory cell further comprises: a second pass gate device having a first terminal, a second terminal, and a control terminal, the first terminal of the second pass gate device of the first type memory cell being electrically coupled with the second data node of the first type memory cell; a second reference line landing pad electrically coupled with the reference voltage node of the first type memory cell; and a second word line landing pad electrically coupled with the control terminal of the second pass gate device of the first type memory cell, the second reference line landing pad of the first type memory cell and the second word line landing pad of the first type memory cell being aligned along the first direction; and the second type memory cell further comprises: a second pass gate device having a first terminal, a second terminal, and a control terminal, the first terminal of the second pass gate device of the second type memory cell being electrically coupled with the second data node of the second type memory cell; a second reference line segment extending along the first direction and electrically coupled with the reference voltage node of the second type memory cell; and a second word line landing pad electrically coupled with the control terminal of the second pass gate device of the second type memory cell, the second word line landing pad and the second reference line segment being spaced apart along the second direction different from the first direction.
 6. The integrated circuit chip of claim 5, wherein the first type memory cell further comprises: a first reference line segment extending along the second direction and electrically coupled with the first reference line landing pad of the first type memory cell; a second reference line segment extending along the second direction and electrically coupled with the second reference line landing pad of the first type memory cell; and a first word line segment extending along the second direction and electrically coupled with the first word line landing pad of the first type memory cell and the second word line landing pad of the first type memory cell; and the second type memory cell further comprises: a third reference line segment extending along the second direction and electrically coupled with the first reference line segment of the second type memory cell and the second reference line segment of the second type memory cell; and a first word line segment extending along the second direction and electrically coupled with the first word line landing pad of the second type memory cell and the second word line landing pad of the second type memory cell.
 7. The integrated circuit chip of claim 1, wherein the second type memory cell further comprises a first bit line segment extending along the first direction and electrically coupled with the second terminal of the first pass gate device of the second type memory cell, the first bit line segment having a line width measurable along the second direction; the first reference line segment having a line width measurable along the second direction; and the line width of the first bit line segment of the second type memory cell is greater than the line width of the first reference line segment of the second type memory cell.
 8. The integrated circuit chip of claim 1, wherein the first type memory cell further comprises: a first reference line segment extending along the second direction and electrically coupled with the first reference line landing pad of the first type memory cell; and a first word line segment extending along the second direction and electrically coupled with the first word line landing pad of the first type memory cell and the second word line landing pad of the first type memory cell; a second reference line segment extending along the first direction and electrically coupled with the first reference line segment of the first type memory cell, the second reference line segment of the first type memory cell being over the first reference line segment of the first type memory cell; and a second word line segment extending along the second direction and electrically coupled with the first word line segment of the first type memory cell, the second word line segment of the first type memory cell being over the second reference line segment of the first type memory cell and first word line segment of the first type memory cell.
 9. An integrated circuit chip, comprising: a first memory device, comprising: a row of first type memory cells, each memory cell of the row of first type memory cells comprising: a first reference line landing pad; a second reference line landing pad; a first word line landing pad, the first reference line landing pad of the memory cell of the row of first type memory cells and the first word line landing pad of the memory cell of the row of first type memory cells being aligned along a first direction; and a second word line landing pad, the second reference line landing pad of the memory cell of the row of first type memory cells and the second word line landing pad of the memory cell of the row of first type memory cells being aligned along the first direction; a first reference line extending along a second direction different from the first direction and electrically coupled with the first reference line landing pad of the memory cell of the row of first type memory cells; a second reference line extending along the second direction and electrically coupled with the second reference line landing pad of the memory cell of the row of first type memory cells; and a first word line extending along the second direction and electrically coupled with the first word line landing pad of the memory cell of the row of first type memory cells and the second word line landing pad of the memory cell of the row of first type memory cells; and a second memory device, comprising: a row of second type memory cells, each memory cell of the row of second type memory cells comprising: a first reference line segment; a second reference line segment; a first word line landing pad, the first reference line segment of the memory cell of the row of second type memory cells and the first word line landing pad of the memory cell of the row of second type memory cells being spaced apart along the second direction; and a second word line landing pad, the second reference line segment of the memory cell of the row of second type memory cells and the second word line landing pad of the memory cell of the row of second type memory cells being spaced apart along the second direction; a first reference line extending along the second direction and electrically coupled with the first reference line segment of the memory cell of the row of second type memory cells and the second reference line segment of the memory cell of the row of second type memory cells; and a first word line extending along the second direction and electrically coupled with the first word line landing pad of the memory cell of the row of second type memory cells and the second word line landing pad of the memory cell of the row of second type memory cells.
 10. The integrated circuit chip of claim 9, wherein a memory cell of the row of first type memory cells has a cell height measurable along the first direction and a cell width measurable along the second direction; a memory cell of the row of second type memory cells has a cell height measurable along the first direction and a cell width measurable along the second direction; and the cell width of the memory cell of the row of first type memory cells is less than the cell width of the memory cell of the row of first type memory cells.
 11. The integrated circuit chip of claim 9, wherein the first word line of the first memory device has a line width measurable along the first direction; the first word line of the second memory device has a line width measurable along the first direction; and the line width of the second word line of the first memory device is greater than the line width of the first word line of the first memory device.
 12. The integrated circuit chip of claim 9, wherein the first memory device further comprises: a third reference line extending along the second direction, over the first reference line of the first memory device and the second reference line of the first memory device, and electrically coupled with the first reference line of the first memory device and the second reference line of the first memory device; and a second word line extending along the second direction, over the first word line of the first memory device, and electrically coupled with the first word line of the first memory device.
 13. The integrated circuit chip of claim 9, wherein the second memory device further comprises: a second reference line extending along the first direction, the second reference line being made of at least the first reference line segment of a memory cell of the row of second type memory cells; a first bit line extending along the first direction and electrically coupled with the memory cell of the row of second type memory cells; the second reference line of the second memory device has a line width measurable along the second direction; the first bit line of the second memory device has a line width measurable along the second direction; and the line width of the first bit line of the second memory device is greater than the line width of the second reference line of the second memory device.
 14. The integrated circuit chip of claim 9, wherein the first memory device further comprises: a supply voltage line extending along the first direction and electrically coupled with a memory cell of the row of first type memory cells; a bit line extending along the first direction and electrically coupled with the memory cell of the row of first type memory cells; and a write assist circuit electrically coupled with the supply voltage line of the first memory device or the bit line of the first memory device; and the second memory device is free from having a counterpart circuit of the write assist circuit of the first memory device.
 15. The integrated circuit chip of claim 14, wherein the write assist circuit IS configured to set a voltage level of the bit line of the first memory device to be less than a ground reference level or to set a voltage level of the supply voltage line of the first memory device to be less than a supply voltage level.
 16. An integrated circuit chip, comprising: a first memory device having a plurality of first type memory cells, wherein: a plurality of first reference line landing pads and a plurality of first word line landing pad of the plurality of first type memory cells are based on a first conductive line layout pattern, a first set of cutting layout patterns, and a second set of cutting layout patterns, the first conductive line layout pattern extending along a first direction, each one of the first set of cutting layout patterns and each one of the second set of cutting layout patterns extending along a second direction different from the first direction, the first set of cutting layout patterns and the second set of cutting layout patterns being arranged along the first direction in an alternating manner; and a second memory device having a plurality of second type memory cells, wherein: a plurality of first word line landing pads of the plurality of second type memory cells are based on a second conductive line layout pattern and a third set of cutting layout patterns, the second conductive line layout pattern extending along the first direction, and each one of the third set of cutting layout patterns extending along the second direction.
 17. The integrated circuit chip of claim 16, wherein the plurality of first reference line landing pads and the plurality of first word line landing pad of the plurality of first type memory cells comprise a first conductive line based on the first conductive line layout pattern.
 18. The integrated circuit chip of claim 16, wherein the conductive line comprises Cu, Ni, TaN, TiN, W, or a combination thereof.
 19. The integrated circuit chip of claim 16, further comprising: a plurality of pass gate devices of the plurality of first type memory cells, each pass gate device of the plurality of pass gate devices of the plurality of first type memory cells having a first driving capability; a plurality of pass gate devices of the plurality of second type memory cells, each pass gate device of the plurality of pass gate devices of the plurality of second type memory cells having a second driving capability; and wherein the second driving capability is greater than the first driving capability.
 20. The integrated circuit chip of claim 16, wherein the first memory device further comprises: a supply voltage line extending along the first direction and electrically coupled with a memory cell of a row of first type memory cells; a bit line extending along the first direction and electrically coupled with the memory cell of the row of first type memory cells; and a write assist circuit electrically coupled with the supply voltage line of the first memory device or the bit line of the first memory device; and the second memory device is free from having a counterpart circuit of the write assist circuit of the first memory device. 